Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define INF 1LL<<62
#define inf 1000000007 

ll a[52][52];
int main() {
	ll h,w;
	cin>>h>>w;
	string s[52];
	for(ll i=0;i<h;i++){
		cin>>s[i];
	}
	queue<pair<ll,ll>>ch;
	ch.push(make_pair(0,0));
	a[0][0]=1;
	ll dh[4]={0,0,1,-1};
	ll dw[4]={1,-1,0,0};
	while(ch.size()!=0){
		ll nowh=ch.front().first;
		ll noww=ch.front().second;
		ch.pop();
		for(ll i=0;i<4;i++){
			ll nexh=nowh+dh[i];
			ll nexw=noww+dw[i];
			if(nowh+dh[i]<0||nowh+dh[i]==h||noww+dw[i]<0||noww+dw[i]==w){
				continue;
			}
			if(a[nexh][nexw]!=0||s[nexh][nexw]=='#'){
				continue;
			}
			a[nexh][nexw]=a[nowh][noww]+1;
			ch.push(make_pair(nexh,nexw));
		}
	}
	if(a[h-1][w-1]==0){
		cout << -1;
		return 0;
	}
	ll ans=0;
	for(ll i=0;i<h;i++){
		for(ll j=0;j<w;j++){
			if(s[i][j]=='#'){
				ans++;
			}
		}
	}
	cout << h*w-ans-a[h-1][w-1];
	// your code goes here
	return 0;
}